Method of manufacture of leakproof inner tubes



w. J. MILESKI 2,581,767

METHOD OF MANUFACTURE OF LEAK-PROOF INNER TUBES Jan. 8, 1952 Filed 001:. 18, 1946 INVENTOR. WILL/AM cl MILES/(l.

Patented Jan. 8, 1952 UNITED STATES PATENT OFFICE METHOD oF MANUFACTURE oFf LEAKBROQF INNER TUBES William Mileski, Norwich, Conn. ApplicationOctober 18, 1946, Serial No. 703,944

- This invention relates to a method of manufacture of a leak proof inner tube and more particularly to the method of constructing a leak proof inner tube for tires.

.Leak proof tubes have been heretofore produced having a liner secured to the outer surface of the tube and which consists of a plastic material that retains a characteristic of flowability and operates to seal a puncture in the tube by flowing into the opening caused by the puncture.

As. heretofore constructed, however, the sealing'liner and the tube have both been placed in an uncured condition within a mold and then vulcanized together in a single operation to a fully cured condition in which the tube and the liner are adhered together. Such method of vulcanizing the liner and the tube together has not proved satisfactory for the reason that, since Claims. (o1.'1s4

the liner when applied over the tube forms an uneven cross-sectional area around the tube which is thickest at the portion of the tube where the liner is applied, the heat of the vulcanizing process fails to penetrate through said thick portion to the same degree that it penetrates the remaining portion of the tube. Therefore, the result obtained by the heretofore used method of vulcanizing such tubes has resulted in tubes which were overeured at their thin portions and undercured at their thick portions so that the life of the tubes has been drastically reduced for the reason that the different undercured and overcured portions remained, respectively,'in a gummy condition which greatly reduced their strength and durability and in many cases were easily deformed or broken due to the uncured or overcured condition of the material and particularly that of the rubberftube itself.

The primary object of this invention, therefore, is to provide a tube having a sealing liner vulcanized thereto and in which boththe tube and the liner are cured to the proper degree for providing normal resiliency, flexibility and strength in the material of the tube and at the thickest portion thereof as well as at the thin portion. 7

A further object of this invention is to provide a. method of vulcanizing or curing the said tubes in a manner which will produce a fully and evenly cured tube and liner throughoutall of the portions thereof.

Further objects and advantages of this inventlon will be more clearly understood from the following description and from the accompanying drawings, in which Fig. 1 is a front view of one form of a vulcanizingiappa'ratus that may be used in'connection' with my invention. Fig. 2 is a side view thereof, partially'in central vertical section.

, Fig. 3 is an enlarged fragmentary view, in central vertical section, of apart of said apparatus.

Fig. 4 is a fragmentary ,view, in'central vertical section, of a portion of a tube liner embodying my invention.

Fig. 5 is an enlarged fragmentary view, in cen: tral vertical section, of a modified form of a liner.

Fig. 6 is a similar view showing a further modified form of liner.

Fig. '7 is a fragmentary view, in central vertical section, of a portion of an inner tube on the same scale as Figs. 3 and 4.

Fig. 8 is a similar view showing the operation of vulcanizing a liner onto a tube.

- Fig. 9 is a similar view showing the tube in its completed form with the liner vulcanized thereto. j v v e As illustrated in Figs. 1 and 2, apparatus adaptable for'producing liners comprising my invention may be of well known construction and preferably suchas includes a stand 5 upon which is supported a mold casing consisting of a lower half 6, which is supported upon pins '7--7 on said stand, and an upper half 8 hinged to the lower half and securable in closed relation thereto by means of a suitable fastening 9. An inner form,

' in the shape of a wheel [0, is rotatably supported on a post I l. I The said wheel has a contour cor responding to the inner surface of the liner which is to be formed thereon and the mold sections 6 and 8 have inner contours corresponding to the 1 outer surface of said-liner; thereby leaving a A still further object of the invention is to provide a leak proof inner tube for tires having a plastic liner therearoun'd which will remain indefinitely in a viscid state so that it.will{fill an aperture in said tube to prevent leakage of air therefrom,

space between the wheel Ill and the casing sections 6' and 8 corresponding to the cross-sectional formof the liner.

In the production of a liner embodying my invention, the plastic material may be placed upon the outer surface of the wheel I0, as clearly shown in Fig. 3, and the two halves 6 and 8 of the mold casing may then be closed thereover to press the said plastic material upon the contour of the wheel and thereby produce the cross-sectionally crescent shaped liner, as clearly shown inFig. 3.

i The mold casing and wheel may then be heated in any suitable way, such as by placing it in a heatedcha'mber, or bypassing-steam through tub sto suitable ducts associated therewith, to thereby apply heat to the liner for partly curing it to a predetermined degree.

In the form shown in Fig. 4, the liner 20-0, is constructed entirely of a single plastic material which is placed upon the mold as illustrated in terior of the said liner so that a of cured,

rubber will be formed over said liner while the inside material will remain under pressure and a permanently viscid state so that, when a punc W ture occurs through the liner" and leaves an opening in the inner tube, the said plastie material will immediately flow into said opening and ealit: osaihotl ahe e I I the modified io m shown i Fi 5, e e i l her: th e 1 33 5 b cons ruct d ith cove I2 and an outer covering 13 between which c n aine he hl s io ma eri l n the f r h m dified: f show i lh'is- 6.! hQ iIllli Q 1F structed for heavy duty tubes and may comprise n i ner co rin whi h i o he dt a. r mary inner covering l5, a layer or plastic mate a ih tmed ete lesser of inner tub st c It. on out r er of as iomat rial an oh 59 hi h lso he inn c. V e-l5. as. w l as the liners I2'l3, may be made of any material uitab e or he purpose, al hough ithe be n 9 hat, reehlehihheh tu e sto k i entirel h n used. c nne t n th the method provided by my present invention.

The curing of said liner may be performed wi hi the mo d n ap r tus abo d ib or. by other suitable means after the liner has been termed n a o d ce with y: in n i n h ever, it is important, that the said liner be only pa l ur dh or t s ap ed t t er t u h.- e shown. at .20 and ha h u e. tse i. also be only partly cured. It has been found rnpst desirable to cure the liner, as Well as the ub on y fo a pr xi a e y romw on -ha f t 'l'rhIfiCnQllfi-lfifilfs of the de re which. is. de ir the leak proof tube when it has. been completed. After the said liner and, tube have been separately pre-rcured to the, degree above mentioned, the are a ed og h within a m d. of nve tiohel t rm. such as illu t a ed, in. He 8 and airhresoore ma he or}? ed; to heitnhe no der to for-0e. it n o firm o h. act w h nn r, surrfac of the ines as ole lyshow he oi ed i e nd ot .v er heo curel-v r suiteh means, wh le i l the. mo e un il th ir t fully ut oohth i Th s. w l pro ide a o reol tod tu e, as th edintrie. 9.111 wh ch the iner is o late v lo h d: hereto a d in wh ch. both; the lbe: a' 3d,-1in :"a' fully cured clear through all portionsgthereoi e rdlessot heir ary n hi knesses dwit out. n umm oh hortla o re t, spo sv such he ha ee ound meyole oh bes pr ce b h h toio e ed method h rei e be an the. l n ha e n. vu c nized toath r n u l cu ed. a one time n a. single operation.

T ubemar/be r hweood wellhn wnr h: ber material such as normally used in i ubes a d; bov ne a ent. 7 e

. Notadhesiveis-used tw oh httthe hereon-cal amount; oi: Qu c e here reached 4 tube since it has been found that my above described process will provide a highly satisfactory, durable, and practical connection between the two members. However, a suitable adhesive may be used in cases where such is found preferable.

It will be clearly understood from the above description that. my invention provides a novel method which is highly desirableifor evenly curing articles composed of difierent layers of material and/or portions of different thicknesses by f rst separately subjecting each of the layers to a preoperation wherein it is cured for a the total curing ultimately applied "5 0 ion of t9 said artiele, and then completing the curing 7 o r t n ter the members have been joined together.

7 It has been found that the final curing operation, while the two members are joined together, s enti el somoieht or prod cing, a c mple seal e w n. th l ner and. t e tu e n ma. it ll. p oduce. a hig ly efifioient a d. lon las in leak proof tube having a liner thereon which is n a pe manently v scidv oohd tion and whi tu e. a l n the eo are, iul youred to the prop r degr e or he most. sa i factory results.-

I elaim e method of manufactu g a. leakpr o tube oohsistins o a plura ity i love of p astic material producing portigns of' different thickne se in sai tube; the aid method nsisting of p orin e ch-oi. e' layers heiore they ar joined. toge h r, then join ns the toge her. and then. com leting, he our e operation- 2-. The m tho of Wi s a leeknrooi inner tube having a. liner. oi cid. p a tic het r -l which onsi ts oi iorm ng said ner f p c material, a d. wi mold hile free of a curing agent, applying a curing agent upon the outer surface oi saidliner, heating said liner under pressure to, partly cure the exter o th r of and. thereby provide a skin over a core or: viscid, material, then applying said partly'cured l ner t a. part y ured in r tu e and. vulo i r n t e tube o ether while comp et n he ur h o sai 'l n r. and tu e,- v r 3. The method of uniting a puncture, sealing, material to a rubber tube, thesaid method com.- prising. the steps, of forming a liner of uncurable viscid plastie v material, applying a curing agent to the surface of said linerto render curable that portion of thematerial which isadjacent the sur.. fa e of the lin r h a in he h rl u il the s d p rtion themate t e i pe m-y cu ed and h reby rz ov d ns a oft par ly cu ed, materiel o e a portion o uncurable, viscid plastic material within the liner, heating the tube untilsit is par't 3 h e, and then ehh y hs h par ly ure skin a ai st. e p rtly cu e ube and further a ng sa d sk nand. tubeioinn r e. he metho o unit n a nn r who: o e a l er foreee hs enomes i e olo he said method 7 including the, steps, oi forming; the liner of an uncurable viscid plastic material, ap: p y ng e urin a n ove he urfac or said l ne nd; he e y r nde ing curab he orti n of he. se ma er alad a ent t su ace o he line he ng eiol erto ro ide. a. partly cured encasing skin over the viscid materiaL, heating the tube until it,is partly cured, and than applyi 21. 6 ne We l the.- tubeand. further: heat? n hem; oint y to secure. th e o the.- ith 'Q tl heand'liner en -a therelo5!: mo hiesorelth which the tube and the skin of the linenare substantially uniformly cured and a permanently viscid material is contained within the said skin.

5. The method of forming a puncture sealing liner for a rubber tube which includes the steps of forming the liner of an uncurable viscid sealing material, applying a curing agent to the surface of said liner to render curable the portion of said material adjacent said surface, heating said liner to cure the curable portion of the material and thereby provide an encasing skin for said sealing material, and applying said liner to said tube.

WILLIAM J. MILESKI.

REFERENCES CITED UNITED STATES PATENTS Name Date Marks Nov. 27, 1906 Number Number Name Date 1,217,888 Wildman et a1. Feb. 27, 1917 1,237,698 Reuter Aug. 21, 1917 1,244,236 Oberfelder Oct. 23, 1917 1,462,452 Kilborn et a1. July 17, 1923 1,470,442 Grosjean Oct. 9, 1923 1,498,017 Crombie et a1. June 17, 1924 1,958,131 Davidson May 8, 1934 2,099,514 Eberhard Nov. 16, 1937 2,231,182 Eger Feb. 11, 1941 2,337,985 Freedlander Dec. 28, 1943 2,354,424 Novotny et a1. July 25, 1944 2,372,382 Krusemark Mar. 27, 1945 2,392,590 Hulswit et a1. 'Jan. 8, 1946 2,418,025 Garvey 1 Mar. 25, 1947 OTHER REFERENCES Ser. No. 373,283, Grabec (A. P. C.), published May 11, 1943. 

1. THE METHOD OF MANUFACTURING A LEAKPROOF TUBE CONSISTING OF A PLURALITY OF LAYERS OF PLASTIC MATERIAL PRODUCING PORTIONS OF DIFFERENT THICKNESSES IN SAID TUBE; THE SAID METHOD CONSISTING OF PARTLY CURING EACH OF SAID LAYERS BEFORE THEY ARE JOINED TOGETHER, THEN JOINING THEM TOGETHER, AND THEN COMPLETING THE CURING OPERATION. 